United States Veterans Administration Pension Payment Cards, 1907-1933 at FamilySearch (not yet complete). From National Archives (NARA) microfilm publication M850. This database has indexed images of cards used by the Bureau of Pensions and Veterans Administration to record the payment of pensions to veterans, or their widows or other dependents. Includes some (but not all) Union veterans.

Confederate:Missouri Confederate Civil War Service Records contains scanned documents of the service records from National Archives microfilm publication M322 (you can obtain copies of the records online for a fee) note: some service records can be 20-30 pages long